Amazon.com Inc. is ratcheting up the pressure on one of the country's largest book publishers, Hachette Book Group, as the retailer seeks to improve its cut of e-book prices.

On Friday, Hachette, a unit of Lagardère SCA, which publishes such writers as James Patterson and Michael Connelly, said that Amazon is no longer allowing its customers to preorder coming titles. A spokeswoman for Amazon declined to comment.